1. Field of the Invention
Embodiments of the present invention generally relate to low-output voltage converters. More specifically, embodiments of the present invention relate to a low-output voltage converter, delivering voltage power down to, or less than, 1 VDC, utilizing distributed secondary circuits.
2. Description of the Related Art
The use of voltage converters is well known where a particular voltage is needed for a specific application and differs from the obtainable source voltage. The use of inductively coupled conductors, or transformers, for general step-up or step-down voltage control has been known in the industry for quite some time. However, as energy consumption and power control have evolved, so has the need for improved and effective power management.
Much of the attention in power management has been surrounding increased demand on large power supplies. For example, as society's need has increased for more power, the development of alternative high energy sources has been the center of attention. With the advent of nuclear power facilities, and other massive sources of energy, the focus of much of the developments in power management has been to regulate such power sources to distribute controllable levels of power throughout existing power grids.
However, over the past few decades, as computer and electrical components have become a center of consumer demand, attention has shifted to the delivery of low voltage output from an industry-standard or readily manageable voltage source. As components for computers and electrical devices become smaller and smaller, the need for more effective low output power control is becoming increasingly significant. This is particularly manifest in applications requiring a very low output voltage, i.e., around 1 VDC or less, from a standard or common input source voltage, e.g., 110 or 220 VAC.
FIG. 1 depicts a schematic of a known embodiment of a low output voltage converter. As is known in the industry, delivery of very low DC voltage power, i.e., less than 1 VDC, is often hampered by the effective control range of the power conversion circuits employed. In view of the schematic of FIG. 1, the primary circuit of a power converter may comprise an excess of circulating energy caused by transformer series leakage inductance, due to realities of flux performance from the primary winding at the transformer, and additionally due to secondary circuit wiring inductance. As the leakage inductance and secondary circuit wiring inductance increases, the efficiency of the overall system decreases, thus making constant power regulation more difficult. In addition, the increased inductance in the primary circuit will generally yield a loss of energy that potentially could be transferred on a switching cycle-by-cycle basis, thus further decreasing the efficiency of the system.
Beyond the likely energy losses in the known voltage converter of FIG. 1, issues may arise where there is a significant step down in voltage across the transformer, causing a significant increase in current through the secondary circuit. A common understanding of power conservation in a step-down voltage converter provides:
                    V        p            *      x              V      s        =            I      s              I      p      Where Vp is the input voltage to the primary circuit, Ip is the current in the primary circuit, Vs is the output voltage at the secondary circuit, Is is the current in the secondary circuit, and x is the efficiency factor (taking into account the aforementioned leakages, among others). Thus, assuming a constant efficiency factor, as the ratio between input to output voltage increases, the ratio of output to input current inversely increases.
In particular embodiment, for example, where a very low output is demanded (e.g., Vs=1 VDC) from a high source voltage (e.g., Vp=220 VAC), the current through the secondary circuit can be quite high. As such, in known voltage converters, the components of the secondary circuit must be sized to carry the entire output current. In many instances, this size requirement prevents the components from being capable of fitting within a particular device or housing for a device that would require such low output voltage. Therefore, the manufacturer of such known voltage converters either must manufacture large components to safely handle the expected current load or must utilize smaller components and risk a current overload, possibly resulting in excessive and dangerous heat dissipation, and possible destruction of the circuit.
Thus, there is a need for an improved low output voltage converter, utilizing distributed secondary windings for effective current regulation.